{"title":"Couple Stress Theory For Materials With Microstructures","authors":"S. Eskandari, H. Akbarzadeh","doi":"10.32393/csme.2021.77","DOIUrl":"https://doi.org/10.32393/csme.2021.77","url":null,"abstract":"","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"22 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130463737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The microstructure of catalyst layers (CLs) plays a significant role in the transport and electrochemical phenomena, which determines the performance and durability of PEM fuel cells. The microstructure of the CLs is sensitive to the fabrication processes, which can be affected by materials, formula, instruments, procedures and conditions. However, it is still challenging to quantitatively describe the microstructure of the CLs, and there is still no consensus on what the optimal CL microstructure is. This presentation reviews the advanced visualization and characterization techniques for the solid and porous microstructure of CLs. The solid and porous microstructure determines the transport and electrochemical phenomena in PEM fuel cells. The structure-determined transport coefficients and electrochemical properties of the CLs are comprehensively examined, and their relation with the structural parameters is reviewed. The inhomogeneous microstructure of CLs also affects the performance of PEM fuel cells, which further determined the degradation rates of the long-term performance. The relation among the microstructure, performance and durability is analyzed based on the literature studies. Finally, the challenges and future directions of the studies on the CL microstructure are explained.
{"title":"Effect Of Microstructure On The Transport Coefficients, Electrochemical Properties, Performance And Durability Of Catalyst Layers In Pem Fuel Cells","authors":"Jian Zhao, Huiyuan Liu, Xianguo Li","doi":"10.32393/csme.2021.204","DOIUrl":"https://doi.org/10.32393/csme.2021.204","url":null,"abstract":"The microstructure of catalyst layers (CLs) plays a significant role in the transport and electrochemical phenomena, which determines the performance and durability of PEM fuel cells. The microstructure of the CLs is sensitive to the fabrication processes, which can be affected by materials, formula, instruments, procedures and conditions. However, it is still challenging to quantitatively describe the microstructure of the CLs, and there is still no consensus on what the optimal CL microstructure is. This presentation reviews the advanced visualization and characterization techniques for the solid and porous microstructure of CLs. The solid and porous microstructure determines the transport and electrochemical phenomena in PEM fuel cells. The structure-determined transport coefficients and electrochemical properties of the CLs are comprehensively examined, and their relation with the structural parameters is reviewed. The inhomogeneous microstructure of CLs also affects the performance of PEM fuel cells, which further determined the degradation rates of the long-term performance. The relation among the microstructure, performance and durability is analyzed based on the literature studies. Finally, the challenges and future directions of the studies on the CL microstructure are explained.","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127854342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamic overflow leakage phenomenon has been introduced in Archimedes screw generator research, but it has not been discussed in the literature in much detail. The authors sought to examine this phenomenon in greater detail by computational fluid dynamic (CFD) studies supported with experimental observations. The CFD results indicated that surface roughness had a significant impact on frictional power losses as well as overflow leakage in Archimedes screws. The results gathered and documented in this study will aide in further performance predicting model development to optimize the design and power production of Archimedes screw generator powerplants. Keywords-Archimedes screw generator; hydrodynamic screw; computational fluid dynamics; microhydro generation; overflow leakage; thin film flow; efficiency; surface roughness
{"title":"Dynamic Overflow Leakage In Archimedes Screw Generators","authors":"S. Simmons, G. Dellinger, A. Aliabadi, W. Lubitz","doi":"10.32393/csme.2021.56","DOIUrl":"https://doi.org/10.32393/csme.2021.56","url":null,"abstract":"The dynamic overflow leakage phenomenon has been introduced in Archimedes screw generator research, but it has not been discussed in the literature in much detail. The authors sought to examine this phenomenon in greater detail by computational fluid dynamic (CFD) studies supported with experimental observations. The CFD results indicated that surface roughness had a significant impact on frictional power losses as well as overflow leakage in Archimedes screws. The results gathered and documented in this study will aide in further performance predicting model development to optimize the design and power production of Archimedes screw generator powerplants. Keywords-Archimedes screw generator; hydrodynamic screw; computational fluid dynamics; microhydro generation; overflow leakage; thin film flow; efficiency; surface roughness","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131680543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Performane Of A Modified Drive Mechanism On A Low Temperature Differential Stirling Engine","authors":"Michael Nicol-Seto, D. Nobes","doi":"10.32393/csme.2021.211","DOIUrl":"https://doi.org/10.32393/csme.2021.211","url":null,"abstract":"","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"40 8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126801147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A downburst is a natural phenomenon that occurs during thunderstorms, creating hazards and damage to infrastructure, notably electricity transmission lines, due to the strong winds produced and the fact that those winds are, laterally, highly correlated compared to everyday synoptic winds. Downbursts are characterized by divergent and generally straight-line winds near the ground, which are naturally observed when several trees in a forest are pushed in one direction. A downburst may be modelled experimentally and also numerically using computational fluid dynamics. One of the experimental methods is the liquid release approach, which consists of releasing a volume of fluid that is slightly denser than the ambient fluid contained in a tank or flume, creating a downdraft that descends to the ground surface. Previous researchers used a solution of water and glycerol as the ambient fluid and an aqueous solution of potassium dihydrogen phosphate solution as the heavier fluid. They proposed length, time, and velocity scaling parameters, R 0 , T 0 , and V 0 , respectively, that allowed comparison of liquid release experiments carried out with different fluid densities, as well as with real events in nature. In addition, these scaling parameters allow comparison of experimental liquid release model data with numerical simulation results. The present project uses these parameters to scale numerical model data obtained by the simulation of a full-scale downburst using a cooling source model. The resulting non-dimensional velocity profiles have similar characteristics to the scaled non-dimensional profiles observed in full-scale field downburst measurements, and similar profiles to data from density-driven downburst experiments. Furthermore, the scaling preserved the vertical location of the near-ground peak wind speed, which is of great interest to wind and structural engineers. These results demonstrated that the scaling parameters, R 0 , T 0 , and V 0 , work well for cooling source downburst simulations. The time scaling parameter T 0 is determined by using the density percentage difference Dr / r obtained from the spatial average of densities within the thunderstorm cloud. This project also examines the influence of the ambient lapse rate on downburst events. Results showed that downbursts are affected by the ambient lapse rate, producing weak peak wind speed when the ambient lapse rate is lower than the dry adiabatic lapse rate, 9.8 K/km. Also, there is a delay in the evolution of the outflow when the ambient lapse rate is lower than the dry adiabatic lapse rate. However, the structure of the downflow and the outflow does not change.
{"title":"Scaling Of Downburst Outflows Simulated Using A Full-Scale Cooling Source Model With Different Ambient Conditions","authors":"C. Kondo, Leigh Orf, E. Savory","doi":"10.32393/csme.2021.161","DOIUrl":"https://doi.org/10.32393/csme.2021.161","url":null,"abstract":"A downburst is a natural phenomenon that occurs during thunderstorms, creating hazards and damage to infrastructure, notably electricity transmission lines, due to the strong winds produced and the fact that those winds are, laterally, highly correlated compared to everyday synoptic winds. Downbursts are characterized by divergent and generally straight-line winds near the ground, which are naturally observed when several trees in a forest are pushed in one direction. A downburst may be modelled experimentally and also numerically using computational fluid dynamics. One of the experimental methods is the liquid release approach, which consists of releasing a volume of fluid that is slightly denser than the ambient fluid contained in a tank or flume, creating a downdraft that descends to the ground surface. Previous researchers used a solution of water and glycerol as the ambient fluid and an aqueous solution of potassium dihydrogen phosphate solution as the heavier fluid. They proposed length, time, and velocity scaling parameters, R 0 , T 0 , and V 0 , respectively, that allowed comparison of liquid release experiments carried out with different fluid densities, as well as with real events in nature. In addition, these scaling parameters allow comparison of experimental liquid release model data with numerical simulation results. The present project uses these parameters to scale numerical model data obtained by the simulation of a full-scale downburst using a cooling source model. The resulting non-dimensional velocity profiles have similar characteristics to the scaled non-dimensional profiles observed in full-scale field downburst measurements, and similar profiles to data from density-driven downburst experiments. Furthermore, the scaling preserved the vertical location of the near-ground peak wind speed, which is of great interest to wind and structural engineers. These results demonstrated that the scaling parameters, R 0 , T 0 , and V 0 , work well for cooling source downburst simulations. The time scaling parameter T 0 is determined by using the density percentage difference Dr / r obtained from the spatial average of densities within the thunderstorm cloud. This project also examines the influence of the ambient lapse rate on downburst events. Results showed that downbursts are affected by the ambient lapse rate, producing weak peak wind speed when the ambient lapse rate is lower than the dry adiabatic lapse rate, 9.8 K/km. Also, there is a delay in the evolution of the outflow when the ambient lapse rate is lower than the dry adiabatic lapse rate. However, the structure of the downflow and the outflow does not change.","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121316456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Achieving a proper knowledge of water/substrate interfaces at the molecular-scale is essential in numerous areas of science. Recently, several experimental studies have been performed on the water density profile at a solid interface. The uncertainties associated with experimental studies on water at a solid interface calls for numerical simulations, which can provide a detailed and reliable understanding of how varying parameters at molecular scales affect the water density profile at a solid interface. The aim of this work is to investigate the microscopic structure of water at a solid surface, using molecular dynamics simulations. In particular, the water density profile at a solid substrate as a function of the hydrophobicity or hydrophilicity of the surface, which is often associated with the surface energy of the substrate ( 𝑆𝐸 𝑠 ), is investigated. The substrate material chosen is silver, which is originally a high energy material with surface energy equal to 𝑆𝐸 𝐴𝑔 . The surface energy of the substrate is modified to adjust the strength of interaction energy between water and surface. The results show that the water density profile as a function of the vertical distance from the substrate (+ z ) depends on the surface energy of the substrate. There are two peaks in the water density profile at z = 2.5 Å and z = 5.5 Å for the unmodified silver substrate ( 𝑆𝐸 𝑠 = 𝑆𝐸 𝐴𝑔 ) indicating that the water molecules form a double-layer structure. The double-layer structure and the vertical distance of each layer from the substrate remains unchanged but the density of both layers decreases when 𝑆𝐸 𝑠 decreases to 40% of its initial value. The second layer at z = 5.5 Å disappears when 𝑆𝐸 𝑠 is reduced to 20% of its original value. The layered structure disappears when 𝑆𝐸 𝑠 reduces to 10% of its original value, and the water density becomes lower that its bulk value for z < 3 Å. The results indicate that on both hydrophobic and hydrophilic surfaces, interfacial water layers possess properties different from those of the bulk water. On hydrophobic surfaces, weakening of water-surface interaction strength results in dewetting and a water-vapor interfacial
{"title":"Effects Of Surface Energy Of Substrate On Water Density Profile At A Solid Interface","authors":"Milad Khodabakhshi, J. Wen, Z. Tan","doi":"10.32393/csme.2021.14","DOIUrl":"https://doi.org/10.32393/csme.2021.14","url":null,"abstract":"Achieving a proper knowledge of water/substrate interfaces at the molecular-scale is essential in numerous areas of science. Recently, several experimental studies have been performed on the water density profile at a solid interface. The uncertainties associated with experimental studies on water at a solid interface calls for numerical simulations, which can provide a detailed and reliable understanding of how varying parameters at molecular scales affect the water density profile at a solid interface. The aim of this work is to investigate the microscopic structure of water at a solid surface, using molecular dynamics simulations. In particular, the water density profile at a solid substrate as a function of the hydrophobicity or hydrophilicity of the surface, which is often associated with the surface energy of the substrate ( 𝑆𝐸 𝑠 ), is investigated. The substrate material chosen is silver, which is originally a high energy material with surface energy equal to 𝑆𝐸 𝐴𝑔 . The surface energy of the substrate is modified to adjust the strength of interaction energy between water and surface. The results show that the water density profile as a function of the vertical distance from the substrate (+ z ) depends on the surface energy of the substrate. There are two peaks in the water density profile at z = 2.5 Å and z = 5.5 Å for the unmodified silver substrate ( 𝑆𝐸 𝑠 = 𝑆𝐸 𝐴𝑔 ) indicating that the water molecules form a double-layer structure. The double-layer structure and the vertical distance of each layer from the substrate remains unchanged but the density of both layers decreases when 𝑆𝐸 𝑠 decreases to 40% of its initial value. The second layer at z = 5.5 Å disappears when 𝑆𝐸 𝑠 is reduced to 20% of its original value. The layered structure disappears when 𝑆𝐸 𝑠 reduces to 10% of its original value, and the water density becomes lower that its bulk value for z < 3 Å. The results indicate that on both hydrophobic and hydrophilic surfaces, interfacial water layers possess properties different from those of the bulk water. On hydrophobic surfaces, weakening of water-surface interaction strength results in dewetting and a water-vapor interfacial","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"301 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122315448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analyzing Robustness Of Granular Agrochemicals: Basis For The Development Of A Pneumatic Spot Applicator","authors":"C. MacEachern, T. Esau, Q. Zaman","doi":"10.32393/csme.2021.71","DOIUrl":"https://doi.org/10.32393/csme.2021.71","url":null,"abstract":"","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131435208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Three-Dimensional Dynamics Of Unicycle: Nonlinear Model And Its Simulation Results","authors":"C. Pethrick, R. Budiman","doi":"10.32393/csme.2021.176","DOIUrl":"https://doi.org/10.32393/csme.2021.176","url":null,"abstract":"","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131499667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Deposition Of A Circular Liquid Jet On A Moving Wall","authors":"Xiaohe Liu, S. Green, N. Balmforth, B. Stoeber","doi":"10.32393/csme.2021.54","DOIUrl":"https://doi.org/10.32393/csme.2021.54","url":null,"abstract":"","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"264 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131519962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Montgomery, Samira Vakili, B. Lanting, R. Willing
{"title":"Force Characterization Of Soft Tissues In The Post-Tkr Knee During Activities Of Daily Living","authors":"L. Montgomery, Samira Vakili, B. Lanting, R. Willing","doi":"10.32393/csme.2021.205","DOIUrl":"https://doi.org/10.32393/csme.2021.205","url":null,"abstract":"","PeriodicalId":446767,"journal":{"name":"Progress in Canadian Mechanical Engineering. Volume 4","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127987271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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